Light guide plates can emit incident light from its light emitting surface almost uniformly, and therefore, are employed in liquid crystal display devices, lighting devices, etc. Once light from a light source enters a light incident surface provided on a side of a light guide plate, the light repeats reflection between a pair of main surfaces of the light guide plate that face each other to propagate in the light guide plate in the direction (propagation direction) substantially orthogonal to the light incident surface. The light propagating in the light guide plate is emitted from the light emitting surface little by little by optical operation as propagation proceeds in the light guide plate. Note that a diffuser plate is provided between the light guide plate and a liquid crystal display element in typical liquid crystal display devices to allow light from a light source to be emitted uniformly to the liquid crystal display element.
It has been known that a dot pattern in which dots increase in area with the distance away from the light incident surface is formed on a main surface of the light guide plate (Patent Literature 1). Patent Literature 1 discloses that the dot pattern is printed on a surface facing the light emitting surface.